Interactive communication system, communication equipment and communication control method

ABSTRACT

Communications from a transmission side to a reception side neither changing the format of voice code data nor requiring another transmission path or increasing the transmission quantity of control information are controlled utilizing information obtained on the reception side. A system includes a first communication equipment provided with a control information embedding unit for embedding control information that is used for a control of communications from a communication partner to the own communication equipment and that is obtained on the own communication equipment side in the communication data to be transmitted to the communication partner side and a second communication equipment provided with a communication control unit for controlling communications to the first communication equipment side using control information transmitted from the first communication equipment.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of international PCT application No.PCT/JP02/11107 filed on Oct. 25, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an interactive communication system.Specifically, it relates to an interactive communication system, acommunication equipment and a communication control method, in thissystem. According to this interactive communication system, in the casewhere communications are implemented while other optional data isembedded in voice coded data, for example, in an interactive packetvoice transmission system, etc., control information that is used for acontrol of communications from a transmission side to a reception sideand that is obtained on the reception side is embedded instead of theother optional data and then this embedded data is transmitted to thetransmission side, thereby controlling the communications on thetransmission side using the control information.

2. Description of the Related Art

Along with the popularization of a computer and the Internet in recentyears, an electronic watermark technology of embedding special data inmultimedia contents (still image, animations, audio, voice, etc.) hasbeen paid attention to. In many cases, such a technology aims atcopyright protection that prevents illegal copy or falsification of databy embedding the name of a producer or a distributor of the contents inthe contents. In addition, this technology aims at increasing the user'sconvenience when he or she uses the contents by embedding informationrelated to the contents and additional information.

Also, in the field of a voice communication such as VoIP (voice-over IP)used as a technology of transmitting and receiving voice data using anIP (Internet protocol) network, a system of embedding optional data invoice data and transmitting the thus-embedded data is used. FIG. 18shows a conventional example of a voice communication system to whichsuch a technology of embedding data is applied.

In, FIG. 18, a voice codec (coder) 50 embeds the optional data seriesother than voice in a voice code and transmits the thus-embedded code toa communication partner side at the time of coding the input voice froma user 1 into a voice code. If data can be embedded without changing theformat of the voice code at that time, the information amount of thevoice code is not increased.

A decoder 51 extracts the embedded optional data series from thetransmitted voice code and at the same time it outputs the reproducedvoice to a user 2 based on a general decoding operation. If theembedding of data is implemented without exerting an influence on thequality of the reproduced voice, there is almost no difference betweenthe voice quality of the reproduced voice and that before the embeddingoperation is implemented. According to the above-mentionedconfiguration, optional data can be transmitted separately from thevoice without increasing the transmission amount of data. Therefore, forthe third person who does not know that data is embedded, thistransmission is recognized as a general voice communication.

Furthermore, the various methods are used for the improvement oftransmission efficiency and voice quality in a voice communicationsystem. As one of these improvement methods, there is a method ofimplementing a transmission control on a transmission side utilizing theinformation that is obtained on a receive side. For example, a method ofsuitably changing the amount of information that is transmittedaccording to the condition of a transmission path (communication line)is used. FIG. 19 shows the first conventional example of a voicecommunication system that implements such a transmission control. Inorder to simplify the explanation in FIG. 19, the control informationthat is used for the control of the communications from a side A to aside B is obtained on the side B as B-side information, but it isnatural that the reverse case is present.

In FIG. 19, information about the condition of a transmission path canbe obtained on the side B from the information about voice data that isreceived from the side A. For example, in VoIP, information about thedelay, the fluctuation and the error rate of a transmission path can beobtained from the header information of a transmission packet. Thesepieces of transmission path information are transmitted to the side Avia a control data circuit and they are used on the side A for atransmission control by a transmission control unit 52.

In this way, it is possible to implement a suitable transmissioncontrol. For example, in the case where the load of a transmission pathis large, a voice line is first secured by decreasing a transmissionamount even if sound quality deteriorates. Furthermore, in the casewhere the load is small, sufficient sound quality is secured byincreasing the transmission amount.

FIG. 20 shows the second conventional example of an interactive voicecommunication system that implements such a transmission control. In thesame drawing, the B-side information is not transmitted to the side Avia an exclusive control data line as shown in FIG. 19 but it ismultiplexed together with voice data by a multiplexing unit 53 using amultiplex line and then the thus-multiplexed data is transmitted.Subsequently, the transmitted data is demultiplexed by a demultiplexingunit 54 on the side A to be used for a transmission control.

There are following four documents as conventional technologies relatedto the embedding of data. At first, a document 1 discloses an imagecoding apparatus that embeds the other kind of information in imageinformation for one screen and compression-codes the embeddedinformation. In other words, this technology discloses a technology ofreplacing the subordinate digit of the transformation coefficient thatsatisfies a specified criterion in respect of alternate components, withthe partial information that is clipped from the other information, fromamong transformation coefficients generated by discrete cosinetransformation.

In a document 2, a voice communication method of implementingcommunications by embedding the bits that configure data obtained bycoding character information, image information, etc. in low n bits ofdigital voice data.

A document 3 discloses a technology of transmitting nonverbalinformation with the bit that is assigned to the output or outputs ofone or both codebook(s) by setting the gains of an adaptive codebook anda fixed codebook that are described later at 0 in preferred embodimentsof the present invention while targeting a radio voice channel.

A document 4 discloses an electronic watermark technology using aspecified key that is shared with a transmission side and a receptionside while targeting a CELP (code excited linear prediction) codingsystem which is described later.

Document 1: Japanese patent application laid-open publication No.2000-287209, “Image coding apparatus, image decoding apparatus, imagecoding method and image decoding method”

Document 2: Japanese patent application laid-open publication No.9-214636, “Voice communication method and apparatus of embedding data”

Document 3: Japanese patent application laid-open publicationNo.2000-209663, “Method of transmitting nonverbal voice information onvoice channel”

Document 4: Japanese patent application laid-open publication No.11-272299, “Embedding method of watermark bit when voice is coded”

The following is the explanation of the problems of the above-mentionedconventional technologies. First of all, in the conventional examplesexplained in FIGS. 19 and 20, an exclusive control data line is requiredor multiplexed transmission with voice information is required in orderto transmit control information from a reception side to a transmissionside. Therefore, there is a problem such that another transmission pathis secured or the increase of transmission amount for the transmissionof control information in addition to the voice information should beconsidered as mentioned above.

In the documents 1 and 2, an embedding parameter such as the embeddingposition of other data in image data or in voice data is defined inadvance on a transmission/reception side and then the embedding andextraction of data are implemented. In the case where the embeddingposition of such data, for example, the value of n is changed in thedocument 2, it is necessary to transmit the changed value as a controlparameter from, for example, a transmission side. In the case where suchdata disappears due to the condition of a transmission path, therearises a problem such that it is difficult to precisely determine on areception side in which position of the received voice code the data isembedded.

It takes a time for a transmission parameter to return to a normal valueespecially in the case where the condition of the past frame effects onthe condition of the present frame. In respect of voice data, an errorconcealment technology of preventing the extreme deterioration of thesound quality can be also applied but problems regarding thetransmission parameter or embedded data still remain.

Furthermore, in the documents 2 and 3, there is a problem such that thedeterioration of a voice signal is generated due to the size of thevalue of n. Also in the document 4, there is a problem such that thepossibility of voice deterioration by embedding data is high since thepresence or non-presence of data is controlled with probabilitycorresponding to the position of the pulse of a fixed codebook inaddition to a problem such that data can be falsified or the like bystealing a key.

The subject of the present invention is to implement a control ofcommunications from a transmission side to a reception side by neitheradditionally securing a transmission path for transmitting the controlinformation nor increasing a transmission amount due to the controlinformation utilizing the information that is obtained on the receptionside while the above-mentioned problem is considered and the format ofvoice code data remains as it is.

Another subject of the present invention is to prevent the disappearanceof the embedded data by re-transmitting the embedded data even in thecase where a communication error is generated due to the condition of atransmission path.

SUMMARY OF THE INVENTION

The communication equipment of the present invention configures aninteractive communication system, that is, a system of including aplurality of communication equipments that are connected to each othervia a communication line and this equipment is provided with at least acontrol information embedding unit.

The control information embedding unit embeds control information thatis used for a control of communications from a transmission side andthat is received on a reception side, in transmission data to betransmitted to the transmission side via a communication line, forexample, this unit embeds information showing the condition of acommunication line from the transmission side to the reception side ascontrol information.

In the interactive communication system of the present invention, atleast the first communication equipment and the second communicationequipment are connected via a communication line. The firstcommunication equipment is provided with a control information embeddingunit embedding control information that is used for a control of thecommunications from the second communication equipment to the owncommunication equipment and that is obtained by the own communicationequipment, in the communication data to be transmitted to the secondcommunication equipment. The second communication equipment is providedwith a communication control unit controlling the communications fromthe own equipment to the first communication equipment using thetransmitted control information.

The communication control method of the present invention comprises astep of embedding the control information that is used on the firstcommunication equipmentside for a control of the communications from thesecond communication equipmentside and that is obtained on the receptionside, in the communication data to be transmitted to the secondcommunication equipment and a step of controlling on the secondcommunication equipment, the communications to the first communicationequipmentside using the transmitted control information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that shows the principle configuration of thepresent invention;

FIG. 2 is a block diagram that shows the first fundamental configurationexample of an interactive communication system of the present invention;

FIG. 3 is a block diagram that shows the second fundamentalconfiguration example of the interactive communication system of thepresent invention;

FIG. 4 is a diagram that explains the encoding process of a CELP voicecoding system;

FIG. 5 is a diagram that explains the decoding process of the CELP voicecoding system;

FIG. 6 is a diagram that shows the standard format of a voice code inpreferred embodiments of the present invention;

FIG. 7 is a diagram that shows the position of a pulse in an algebraiccodebook;

FIG. 8 is a diagram that shows the voice code format in which data isembedded according to the preferred embodiments of the presentinvention;

FIG. 9 is a diagram that explains the control code in FIG. 8;

FIG. 10 is a configuration block diagram that shows a first preferredembodiment of the present invention of the interactive communicationsystem;

FIG. 11 shows a flowchart of the processes of an embedding control unit;

FIG. 12 a flowchart of the processes of an extraction control unitbefore an error is detected;

FIG. 13 is a flowchart of the processes of the extraction control unitafter an error is detected;

FIG. 14 is a flowchart of the processes of a data extraction unit;

FIG. 15 is the configuration block diagram of a second preferredembodiment of the present invention of the interactive communicationsystem;

FIG. 16 is a configuration block diagram that shows a third preferredembodiment of the present invention of the interactive communicationsystem;

FIG. 17 is a block diagram that shows the functional configuration of anembedding data control unit;

FIG. 18 is a block diagram that explains the application of a dataembedding technology in a conventional voice communication system;

FIG. 19 is a diagram that shows the first conventional example of theinteractive communication system of transmitting control data; and

FIG. 20 is a diagram that shows the second conventional example of theinteractive communication system of transmitting control data.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a basic configuration block diagram of the interactivecommunication system according to the present invention. In the drawing,the (first) communication equipment 1 is provided with a controlinformation embedding unit 3 while the (second) communication equipment2 is provided with a communication control unit 4.

The control information embedding unit 3 embeds the control informationthat is used for a control of communications from the communicationequipment 2 that is a communication partner to the own communicationequipment 1 and that can be obtained on the side of the communicationequipment 1, in the communication data to be transmitted to the side ofthe communication equipment 2. The communication control unit 4 controlsthe communications from the communication equipment 2 to thecommunication equipment 1 using the control information that is embeddedin the communication data to be transmitted from the communicationequipment 1.

In a preferred embodiment of the present invention, the followingconfiguration can be adopted. The communication equipment 1 furthercomprises an error detection unit that detects a communication errorwhen communications are implemented from the communication equipment 2to the communication equipment 1 of FIG. 1 by embedding optional data inthe main communication data. The control information embedding unit 3embeds the error detection information as control information when acommunication error is detected. In addition, the communicationequipment 2 further comprises an embedding re-execution control unitthat controls the embedding re-execution of other optional data,corresponding to the error detection information that is transmittedfrom the communication equipment 1. Furthermore, the communicationequipment 1 comprises an extracted data monitoring unit monitoring thenormal reception amount of other optional data that is embedded in themain communication data transmitted from the communication equipment 2.The control information embedding unit 3 embeds the information aboutthe data normal reception amount before an error is detected in additionto the error detection information when a communication error isdetected. The embedding re-execution control unit on a side of thecommunication equipment 2 also controls the embedding re-execution ofoptional data after eliminating the part that is shown by the datanormal reception amount.

In the present invention, the communication equipment 1 in theinteractive communication system comprises at least the controlinformation embedding unit 3. In the preferred embodiment, the controlinformation that is embedded by the control information embedding unit 3can be the information that shows the condition of a transmission path(communication line) from the transmission side to the reception side.

In the preferred embodiment of the present invention, whencommunications are implemented from the transmission side to thereception side by embedding other optional data in the maincommunication data, it is possible that the communication equipment 1further comprises an error detection unit that detects a communicationerror and the control information embedding unit 3 embeds errordetection information as control information when a communication erroris detected due to the condition of a transmission path. In addition,the communication equipment 1 further comprises a normal data receptionamount monitoring unit that monitors the normal reception amount ofother optional data before a communication data error is detected andthe control information embedding unit 3 further embeds the normalreception amount in addition to the error detection information when acommunication data error is detected.

Furthermore, in the preferred embodiment, when the interactivecommunication system is a voice communication system that uses a CELP(code excited linear prediction) coding system and when other optionaldata is embedded in voice code data, a determination parameter that isused to determine whether or not the embedding operation is implementedin the voice coding data, a threshold used for the determination and adata embedding target parameter in the voice coding data are agreedmutually between the transmission side and the reception side.

In the preferred embodiment, when the control information that is usedfor a control of the communications from the transmission side isobtained on the reception side while implementing communications fromthe reception side to the transmission side after embedding otheroptional data in the main communication data, the control informationunit 3 can embed the control information in preference to other optionaldata.

According to the communication control method of the present invention,this method includes a method of embedding on the first communicationequipment, the control information that is used for the control of thecommunications from the second communication equipment side and that isobtained on a side of the first communication equipment, in thecommunication data that is transmitted to the second communicationequipment, thereby controlling on the second communication equipment,communications to the first communication equipment using the controlinformation that is embedded in the communication data to be transmittedfrom the first communication equipmentside.

According to the present invention, the control information that is usedfor the control of the communications from a transmission side to areception side and that is obtained on the reception side is embedded inthe communication data from the reception side to the transmission sideto be transmitted to the transmission side and then the thus-transmitteddata is used for a control of the communications.

FIG. 2 is a block diagram that shows the first fundamental configurationof an interactive communication system in the preferred embodiment ofthe present invention. In this drawing, interactive communications, forexample, voice communications are implemented between a communicationequipment 11 a on a side A and a communication equipment 11 b on a sideB.

In the same drawing, for the control of communications that areimplemented toward the communication equipment 11 b from thecommunication equipment 11 a, in other words, for the control of thetransmission of a voice code via a voice data line, the information thatis obtained on the side B is used. A data embedding unit 14 embeds theinformation that is obtained on the side B in the input voice that iscoded by a voice codec (coder) 12 b on the side B and the thus-embeddedvoice is transmitted to the communication equipment 11 a on the side Avia the voice data line. In respect of the embedding of the B-sideinformation, a data embedding system using a CELP (code excited linearprediction) system that is described later is used.

On the communication equipment 11 a side, the B-side information fromthe voice code that is transmitted from the side B by a data extractionunit 15 a, that is, the B-side information that is obtained on the sideB and is used for the control of the communications from the side A toside B is extracted. Then, the extracted voice data is decoded by avoice codec (decoder) 13 a and the thus-decoded data is outputted asoutput voice.

The B-side information is given to a transmission control unit 16 andthis information is used for the control of the transmission of thevoice code that is outputted from a voice codec (coder) 12 a to the sideB as the transmission control signal from the transmission control unit16. The voice code that is controlled by the B-side information is givento a voice codec (decoder) 13 b on the side B via the voice data line.The thus-decoded data is outputted as output voice.

FIG. 3 is a block diagram that shows the second fundamentalconfiguration of a communication system in the present embodiment. InFIG. 3, the data embedding unit 14 a in the communication equipment 11 aon the side A embeds the optional data that is given via thetransmission control unit 16, for example, the data of the mediadifferent from the voice, in the voice code data functioning as theoutput of the voice codec (coder) 12 a, which is different from theprocesses in FIG. 2. Then, the embedded voice code data is transmittedto the side B via the voice data line.

The optional data that is embedded is extracted from the voice code databy a data extraction unit 15 b on the side B and the extracted data isused as extraction data on the side B.

In the case where the optional data that is embedded in the voice codedata disappears on the side A as mentioned above, for example, there-transmission of embedded data becomes required. Accordingly, in thecase where a communication error is detected, for example, in the casewhere the omission of the sequence number that is stored in the headerof a transmission packet is detected, the detection result is given aserror information to a data embedding unit 14 b in the communicationequipment 11 b on the side B as information corresponding to the B-sideinformation in FIG. 2. In the same way as in FIG. 2, this information isembedded in the voice coded data to be transmitted to the side A. Then,this error information is extracted by the data extraction unit 15 a tobe given to the transmission control unit 16 and this unit controls theembedding of optional data, that is, the re-transmission of embeddeddata so that the optional data is embedded in the voice coded data to betransmitted once again to the side B.

FIGS. 2 and 3 explain the case where the information that is obtained onthe side B is used as the control information in the communications fromthe side A to the side B. The communications that are implemented hereare interactive communications. On the contrary, it is also possiblethat the A-side information that is obtained on the side A and is usedfor a control of the communications from the side B to the side A isembedded in the voice coded data to be transmitted from the side A tothe side B.

Before further explaining about the preferred embodiments of the presentinvention, a method of embedding data that is used in the preferredembodiments of the present invention is explained in reference to FIGS.4 to 9.

As a method of embedding data, various methods have been proposed. Here,the following is the explanation of a method of embedding data regardinga CELP system that is a base algorism of a voice coding technology suchas G. 729 that is regulated by ITU-T (International TelecommunicationUnion, Telecommunication standardization sector) that is aninternational standardization organization or a voice coding technologysuch as AMR (Adaptive•Multi•Rate) that is regulated by 3GPP (the thirdGeneration Partnership Project) in the field of mobile communications.

The characteristics of this method are as follows: Firstly, it ispossible to embed optional data without changing the format of codeddata. Secondly, it is possible to embed optional data while minimizingthe influence on the reproduction sound quality. Thirdly, it is possibleto adjust an embedding data amount while predicting the influence on thereproduction sound quality. Fourthly, it is possible to apply theabove-mentioned method to a wide range of methods based on a CELPsystem.

FIG. 4 is the diagram explaining a transmission-side processing, inother words, a coding processing of a CELP voice coding system. CELP isa technology of extracting a parameter from inputted voice by making ananalysis using a voice generation model of a human being, therebytransmitting the parameter. At first, an LPC analysis unit 30 extractsan LPC (Linear Prediction Coefficient) from the input voice. Thiscoefficient is obtained by approximating a vocal tract characteristicwhen a human being produces a sound, using an all-pole linear filter.This coefficient is converted into an LSP (Line Spectrum Pair), etc. byan LSP conversion and quantization unit 31 as a parameter that shows afrequency characteristic and then the thus-converted parameter isquantized to be transmitted to the reception side.

Then, a parameter for the sound source signal is extracted. In otherwords, a plurality of candidates is prepared as a codebook. The optimumseries (code word) is selected as a sound source. The selected code wordis transmitted as an index that shows the storage place. The codebookincludes two kinds of codebooks such as an adaptive codebook 34 forexpressing a pitch and a fixed codebook 35 for expressing a noiseseries. Furthermore, the gain for the amplitude adjustment of each codeword is also quantized and the thus-quantized gain is transmitted as aparameter.

FIG. 5 is a diagram explaining a reception-side processing, in otherwords, a decoding processing of a CELP voice coding system. In thisdecoding processing, a processing of simulating a voice generationseries is implemented. In other words, the code words in the adaptationcodebook 43 and the fixed codebook 44 are selected using the index thatis transmitted from the transmission side. Then, a sound source signal Ris generated using both the code word and the information about thegain, thereby reproducing voice by a synthesis filter 41 that uses LPCas the conversion result of the LSP transmitted from the transmissionside. In this way, the transmission parameter that is coded by the CELPsystem corresponds to the characteristic parameter of a voice generationsystem. By using this transmission parameter, reproduction voice isobtained by the following equation.S _(rp) =HR=H (g _(p) P+g _(c) C)

Where S_(rp) is reproduction voice, R is a sound source signal, H is asynthesis filter, g_(p) is an adaptive code word gain, P is an adaptivecode word, g_(c) is a fixed code word gain and C is a fixed code word.

The respective gains regarding two kinds of code words as sound sourcesignals, that is, an adaptive code word corresponding to a pitch and afixed code word corresponding to noise become factors each of whichshows the degree of the contribution to the reproduction voice of eachcode word. In other words, the degree of the contribution of thecorresponding code word becomes small in the case where the gain issmall.

Thereupon, it is determined that the degree of the contribution of thecorresponding code word is small in the case where the gain is equal toor less than a certain threshold using this gain as a determinationparameter. Accordingly, optional data can be embedded instead of theindex regarding the code word. In this way, the influence of embeddingdata can be minimized. Furthermore, an embedding data amount can beadjusted by controlling the threshold while predicting the influence onthe reproduction sound quality.

If only the initial value of the threshold is defined in advance on bothtransmission and reception sides, the writing in/reading out of embeddeddata becomes possible by using a determination parameter as a threshold,an index as a parameter to be embedded or optional data. Furthermore, bydefining a control code, etc. as optional data, the change of athreshold becomes possible so that the transmission amount of theembedded data can be adjusted without transmitting control informationvia another path.

By setting the CELP system as a basic system in this way, it becomespossible to embed optional data in voice code data without changing thevoice code format. In other words, ID and information about the othermedium can be embedded in voice information neither deteriorating thefundamental system in the communication system nor being recognized by auser and then the thus-embedded information can be transmitted.Furthermore, by using a parameter such as a gain, an adaptation/fixedcodebook, etc. that are common in CELP, this system can be applied tovarious systems.

Each of FIGS. 6 to 9 is a diagram explaining a voice code format forembedding data based on the present preferred embodiment. In the presentpreferred embodiment, an algebraic codebook is used as a fixed codebookfor the above-mentioned noise. FIG. 6 shows the standard form of a voicecode format. This drawing shows the case where the embedding of optionaldata is not implemented, and the index and gain of an algebraic codebookare stored in a voice code in addition to the index and gain of anadaptation codebook. The algebraic codebook index is used as anembedding target parameter, in other words, a region where optional datacan be embedded. The algebraic codebook gain is used as a storage regionof an embedding determination parameter, in other words, a parameter tobe compared with a threshold.

Here, the algebraic codebook is further explained using FIG. 7. Analgebraic codebook is used to quantize the noise component that isincluded in a sound source signal and this codebook includes a pluralityof pulses the amplitudes of which are 1 or −1. FIG. 7 shows the positionof a pulse in the algebraic codebook that is adopted in G. 729. In G.729, a frame having a length of eighty samples (10 ms) is divided intotwo sub-frames having lengths of forty samples (5 ms) and the noisecomponent is quantized. Then, four pulses are arranged for eachsub-frame.

In FIG. 7, pulse series 0 to 3 show four pulses and the positions ofpulses that can be arranged from among forty samples are shown for eachpulse.

When an algebraic codebook is retrieved, a combination, such that theerror electric power of input voice becomes minimum in a reproductionregion, is determined from among combinations of the positions andamplitudes (codes) of the above-mentioned pulses. The information aboutthe determined pulse position and the information about the determinedcode are transmitted to a reception side as algebraic codebook indexes.

In the case of G. 729, the positions (eight positions) of the respectivepulses of the pulse series 0 to 2 are quantized with three bits, thepositions (sixteen positions) of the pulses of the pulse series 3 arequantized with four bits and the code (−1 or 1) of each of four pulsesis quantized with one bit. Accordingly, the number of bits of thealgebraic code for each sub-frame becomes seventeen bits and thealgebraic code of thirty-four bits is outputted for each frame.

FIG. 8 shows the frame format in the case where optional data isembedded instead of an algebraic codebook index. In the case where thealgebraic codebook gain as an embedding determination parameter is equalto or less than a predetermined threshold, optional data is embedded inthe position of the algebraic codebook index as an embedding targetparameter as shown in FIG. 6.

As mentioned above, the number of bits of the algebraic codebook indexas an embedding target parameter is thirty-four for each frame. If thethirty-four bits are referred to as M bits, it can be determined fromthe contents of one bit of the MSB whether the embedded data is, forexample, optional data of other media or a control code that is used fora communication control among communication equipments. By setting theMSB at “0”, it is shown that the remaining (M−1) bits are optional datawhile by setting the MSB at “1”, the remaining (M−1) bits are controlcodes.

FIG. 9 is a diagram explaining an example of the contents of a controlcode in FIG. 8. As mentioned above, (M−1) bits that are obtained bysubtracting one bit of MSB from the embedding target parameter of M bitsare used for a storage region of a control code. Furthermore, amongthese (M−1) bits, three bits on an MSB side are used for controlclassification recognition data and other (M−4) bits are used to storecontrol data.

In the present preferred embodiment, at least five types of controlclassification recognition data, such as the embedding start, theembedding termination, the embedding suspension, the embeddingre-transmission start and error detection information are used, threebits of the control classification recognition data are used todistinguish these types.

In the data extraction unit on the reception side, the contents of acontrol can be recognized by referring to this control classificationrecognition data. In the case of error detection information, forexample, information about the normal reception data amount is embeddedin control data to be transmitted, which is described later. In the casewhere specific data is not required as control data, an optional bitseries, for example, a random bit series is stored as control data to betransmitted.

The following is the detailed explanation of the preferred embodiment ofa communication system in the present invention. FIG. 10 is theconfiguration block diagram of a first preferred embodiment of aninteractive communication system. According to the first preferredembodiment, when optional embedding data is embedded in voice code to betransmitted from the side A to the side B in the same way as in FIG. 3,a communication error is generated due to a transmission path error andthis error is detected on the side B. Then, the detected error isembedded in voice code data that is transmitted from the side B to theside A and the embedded data is transmitted to the side A. On the sideA, re-transmission of optional embedded data to the side B isimplemented from the beginning of the embedded data.

Meanwhile, in all the preferred embodiments of the present invention,when a control code such as error detection information is required tobe transmitted while optional embedding data is embedded in voice datato be transmitted from the side B to the side A, the control code isembedded in the storage region of the above-mentioned algebraic codebookindex to be transmitted in preference to the optional data.

In FIG. 10, data extraction units 15 a, 15 b are not directly connectedto a voice data line via which voice code data is transmitted from atransmission side, which is different from in FIG. 3 but the operationsare fundamentally the same as those in FIG. 3. An extraction controlunit 17 b controls the extraction of, for example, optional embeddeddata that is embedded in a voice code data transmitted from the side Aand it controls the opening and closing of a switch S2, therebycontrolling the data extraction by the extraction unit 15 b as explainedin FIG. 11 which is described later. Furthermore, an extraction controlunit 17 a controls, for example, the extraction of the error informationthat is embedded in the voice code data and transmitted from the side B,by the data extraction unit 15 a.

An error detection unit 18 detects a communication error caused by atransmission path error from the voice code data that is transmittedfrom the side A. This error detection method includes an optional methodsuch as a method of detecting the omission of the sequence number of apacket, a method of detecting a bit error of the error-detection codethat is added to, for example, voice code data, etc.

In the case where an error is detected, the error detection unit 18outputs error detection signals to the extraction control unit 17 b andan embedding control unit 19 b. The extraction control unit 17 b opensthe switch S2 and suspends the data extraction by the data extractionunit 15 b. At the same time, the error detection unit 18 directs theembedding control unit 19 b to close a switch S3. Then, the errorinformation that is outputted by an embedded data control unit 20 b isembedded in voice code data by the data embedding unit 14 b to betransmitted to the side A.

On the side A, the error information is extracted by the data extractionunit 15 a from the transmitted voice code data. The thus-extracted errorinformation is given to an embedded data control unit 20 a and this unitcontrols the re-transmission of optional embedded data.

FIG. 11 shows a flowchart of the processes of the embedding controlunits 19 a and 19 b of FIG. 10. When the processing of an input frame isstarted in the same drawing, the value of an algebraic codebook gain isextracted from the voice code data that is inputted from a voice CODEC(coder) in step S1. It is determined in step S2 whether or not the valueof the gain is equal to or less than the threshold. In the case wherethe gain is less than the threshold, a switch S1 or the switch S3 isclosed in step S3 and the processing for the frame terminates. In thecase where the gain is equal to or greater than the threshold in stepS2, the switch S1 or S3 is opened in step S4 and the processing for theframe terminates.

FIGS. 12 and 13 are flowcharts of the processes of extraction controlunits 17 a and 17 b. FIG. 12 shows the processes before a communicationerror is detected while FIG. 13 shows the processes after an error isdetected.

When a processing is started in FIG. 12, the gain of an algebraiccodebook is extracted in steps S6 and S7 in the same way as in FIG. 11and the extracted gain is compared with the threshold. In the case wherethe gain is less than the threshold, it is determined in step S8 whetheror not an error detection signal is received from the detection unit 18.In the case where the signal is not received, the switch S2 or a switchS4 is closed in step S9 and the processing for the frame terminates. Inthe case where the gain is equal to or greater than the threshold instep S7 or in the case where the detection signal is received in stepS8, the switch S2 or S4 is opened in step S10 and the processing for theframe terminates. Meanwhile, the detection of an error is implemented bythe error detection unit 18 before the data extraction is implemented bya data extraction unit and the data decoding is implemented by a voicedecoder.

When the processing is started in FIG. 13, the processes in steps S6 andS7 are implemented. In the case where the value of the gain is less thanthe threshold, an algebraic codebook index, that is, embedded data as anembedding target parameter that is explained in FIG. 8 is extracted instep S11. Then, it is determined in step S12 whether or not a controlcode for starting re-transmission of embedded data that is explained inFIG. 9 is included in the embedded data. In the case where the code isembedded, the switch S2 or S4 is closed in step S9, the processing forthe frame terminates.

Also, in the case where the value of the gain is equal to or greaterthan the threshold in step S7 and in the case where the control code forstarting the re-transmission of embedded data is not included in theembedded data in step S12, the switch S2 or S4 is opened in step S10 andthe processing for the frame terminates. In other words, after an erroris detected, the extraction of data is not implemented by a dataextraction unit until the control code of starting the re-transmissionof embedded data is detected even if the gain is less than thethreshold.

FIG. 14 is a flowchart of processes of the data extraction units 15 aand 15 b. When a processing is started in the same drawing, the embeddeddata corresponding to an algebraic codebook index is extracted in stepS15. In step S16, it is determined whether or not the value of one biton the MSB side is “0”. In the case where the value is “0”, theprocessing for optional extracted data is implemented in step S17 andthe processing terminates. Furthermore, in the case where the value ofone bit on the MSB side is “1”, the processing for the control code isimplemented in step S18 and the processing terminates.

FIG. 15 is the configuration block diagram of a second preferredembodiment of an interactive communication system. When the secondpreferred embodiment in this drawing is compared with the firstpreferred embodiment in FIG. 10, there is a fundamental different pointsuch that an extracted data monitoring unit 21 that is connected to thedata extraction unit 15 b is provided on the side B in FIG. 15. Asexplained in FIG. 9, the extracted data monitoring unit 21 monitors theextracted data amount that is extracted by the data extraction unit 15b, in other words, a normal data reception amount when and after thedata in which a code showing the embedding start as a control code isembedded is transmitted from the side A. When a communication error isdetected by the error detection unit 18, the normal data receptionamount is outputted to the embedded data control unit 20 b. The embeddeddata control unit 20 b adds this normal data reception amount to theerror information only about error detection that is explained in FIG.10 and then this normal data reception amount is stored as the controldata of FIG. 9. Then, the embedding of the data is implemented and thethus-embedded data is transmitted to the side A.

On the side A, the normal data reception amount in the error informationthat is extracted by the data extraction unit 15 a is given to theembedded data control unit 20 a. Then, the embedded data control unit 20a controls the re-transmission of embedded data except for the data thatis already received normally on the side B from among embedded data. Inthis way, the re-transmission of embedded data that is already receivednormally on the side B can be omitted, which is different from the firstpreferred embodiment as shown in FIG. 10.

In the present preferred embodiment, optional data of up to thirty-threebits can be embedded for each frame as mentioned above. Therefore, inthe case where one data to be embedded is mass data, this data to beembedded is divided into a plurality of frames to be embedded.Accordingly, the re-transmission of embedded data can be implemented byeliminating the data that is received normally on the side B. Meanwhile,the processing by the embedded data control unit 20 a is explained inreference to a next third preferred embodiment.

FIG. 16 is the configuration block diagram of the third preferredembodiment of an interactive communication system. In FIGS. 1 to 15, thesimplified explanation is made in such a way that optional data isembedded only in a voice code data transmitted from the side A to theside B in accordance with the fact that communications are implementedbased on an interactive communication system. This third preferredembodiment, however, shows a system configuration in the case whereoptional data is embedded even in the voice code data that istransmitted from the side B to the side A, which is different from thesimplified explanation.

Therefore, in FIG. 16, an error detection unit 18 a and an extracteddata monitoring unit 21 a are provided also on the side A. The followingis the explanation in the case where a communication error caused by atransmission path error, etc. is monitored in the communications fromthe side B to the side A. At first, the communication error is detectedby the detection unit 18 a. The data amount that is extracted on theside A until the communication error is detected, in other words, theA-side normal data reception amount, together with the error informationby a control of the embedded data control unit 20 a is embedded in voicecode data by the data embedding unit 14 a. Then, the thus-embedded datais transmitted to the side B.

On the side B, the re-transmission of the embedded data except for thedata that is normally received before an error is detected on the side Ais controlled by the embedded data control unit 20 b using the A-sidenormal data reception amount in the A-side error information that isextracted by the data extraction unit 15 b. The normal data receptionamount outputted from the extracted data monitoring unit 21 to theembedded data control unit 20 b in FIG. 15 corresponds to the B-sidenormal data reception amount in FIG. 16. Furthermore, the errorinformation that is outputted from the data extraction unit 15 a to theembedded data control unit 20 a corresponds to the B-side errorinformation.

FIG. 17 is the functional configuration block diagram that shows theoperations of an embedded data control unit. In the same drawing, aswitch S turns ON on the side of a terminal b in the case of embeddinggeneral optional data. The optional data that is read in by an embeddeddata reading unit 22 is outputted to a data embedding unit. The embeddeddata reading unit 22 reads in thirty-three bits of embedded data andadds distinction information of one bit, that is, “0” here on the MSBside as mentioned before in order to distinguish optional data from acontrol code, thereby outputting a bit series of thirty-four bits.

A control code generation unit 23 generates a control code as occasiondemands and sends a control code output notice to an output control unit24. Corresponding to this operation, the switch S is turned ON on theside of a terminal a by the output control unit 24 and the control codeis outputted to a data embedding unit.

For example, when embedded data is firstly given to the embedded datacontrol unit 20 a or when the embedding of data to be embeddedterminates, a notice informing whether or not the embedded data ispresent is given to the control code generation unit 23 from theembedded data reading unit 22. Corresponding to this notice, the controlcode generation unit. 23 generates a control code including the controlclassification recognition data that shows the above-mentioned embeddingstart or the embedding termination, thereby outputting this code to adata embedding unit. In other words, this unit generates a control codeof thirty-three bits that include, for example, a random bit seriesaccording to the contents of the control and it adds “1” to the side ofMSB as the recognition information of one bit, thereby outputting a bitseries of thirty-four bits.

In FIG. 16, when the A-side normal data reception amount is given fromthe extracted data monitoring unit 21 to the embedded data control unit20 a, a control code having control data of FIG. 9 in which the A-sidenormal data reception amount is stored is generated by the control codegeneration unit 23 of FIG. 17 and the thus-generated control code isoutputted to the data embedding unit 14 a. Then, the thus-outputted codeis embedded in voice code data to be transmitted to the side B and thethus-transmitted code is extracted by the data extraction unit 15 b onthe side B to be used as A-side error information.

The B-side error information that is given to a B-side error dataprocessing unit 25 of FIG. 17 is given from the data extraction unit 15a of FIG. 16 and it includes the information about the normal datareception amount on the side B. The B-side error data processing unit 25outputs this data reception amount to the embedded data reading unit 22and at the same time it outputs an error notice to the control codegeneration unit 23.

The control code generation unit 23 generates a control code includingthe control classification recognition data used for a re-transmissionstart of the embedded data that is shown in FIG. 9 and it outputs thethus-generated code to the data embedding unit. The embedded datareading unit 22 starts the reading of embedded data by eliminating adata amount that is notified from the B-side error informationprocessing unit 25 and that is normally received on the side B, from thebeginning of the read-in data. Then, the switch S turns ON on the sideof the terminal b after a re-transmission start code of embedded data tothe side B is embedded and the embedded control code is transmitted.Then, the read-in data is outputted to the data embedding unit and theembedding of data in voice code data is resumed.

As mentioned above, a control of the communication system using anembedding data operation in the interactive voice communication systemthat uses a CELP system is explained in detail. The present invention isneither limited to a CELP system nor limited to a voice communicationsystem so that it is natural that the present invention can be appliedto various types of interactive communication systems.

As explained above in detail, according to the present invention, theinformation for controlling the communications from a transmission sidecan be embedded in communication data without changing the format of thecommunication data and the thus-embedded data can be transmitted.Therefore, a communication control on the transmission side can beimplemented utilizing the information that is obtained on the receptionside neither requiring another transmission path for transmitting thecontrol information nor increasing the transmission amount ofcommunication data which is caused by transmitting the controlinformation.

In addition, it becomes possible to re-transmit embedded data bydetecting a communication error on the reception side or re-transmitembedded data by eliminating the data that is normally received beforean error is detected, which greatly contributes the improvement of thepracticality of communications in an interactive communication system.

INDUSTRIAL APPLICABILITY

The present invention is not limited to communication industry the mainbusiness of which is to implement communications so that it can be usedin all kinds of industries that utilize communications such as among amain office and branch offices, among factories, etc. using aninteractive communication system.

1. Communication equipment in an interactive communication systemincluding a plurality of communication equipments that are connected toeach other via a communication line, comprising: an error reception unitto receive reception error information at a reception side; atransmission control unit to control transmission from a transmissionside to the reception side using the reception error information; anerror detection unit to detect transmission error on transmission fromthe reception side; an error notification unit to notify the receptionside of the transmission error when the transmission error is detected;a control information embedding unit to embed control information thatis used for controlling communications from the reception side, in anormal communication data without changing a format of voice code datain a voice communication, wherein the control information that isobtained on the reception side is information that shows a condition ofa communication line from the transmission side to the reception side,wherein the error detection unit detects, when communications areimplemented by embedding other optional data in main communication datain communications from the transmission side to the reception side, anerror of communication data, and wherein, when the error ofcommunication data is detected due to a condition of the communicationline, the control information embedding unit embeds information aboutthe error detection as the control information; and a normal datareception amount monitoring unit to monitor a reception amount of theother optional data before the error of communication data is detected,wherein the control information embedding unit further embeds a normaldata reception amount in addition to the information about the errordetection when the error of communication data is detected.
 2. Thecommunication equipment in an interactive communication system accordingto claim 1, wherein when the interactive communication system is a voicecommunication system that uses a CELP (Code Excited Linear prediction)coding system and the other optional data is embedded in voice codedata, a determination parameter that is used to determine whether or notembedded data is present in a frame, a threshold for the determinationparameter and a data embedding target parameter in a frame are agreedmutually between the transmission side and the reception side.
 3. Thecommunication equipment in an interactive communication system accordingto claim 1, wherein when control information that is used for a controlof communications from the transmission side is obtained whileimplementing communications by embedding still other optional data inmain communication data that is transmitted to the transmission side,the control information embedding unit embeds the control information inpreference to the other optional data.
 4. An interactive communicationsystem including a plurality of communication equipments that areconnected via a communication line to each other, comprising: a firstcommunication equipment provided with: an error reception unit toreceive reception error information at a reception side; a transmissioncontrol unit to control transmission from a transmission side to thereception side using the reception error information; an error detectionunit to detect transmission error on transmission from the receptionside; an error notification unit to notify the reception side of thetransmission error when the transmission error is detected; and acontrol information embedding unit to embed control information that isused for a control of communications from a side of a communicationpartner to an own communication equipment, in a normal communicationdata without changing a format of voice code data in a voicecommunication; a second communication equipment provided with acommunication control unit for controlling communications to a side ofthe first communication equipment using control information embedded incommunication data that is transmitted from the first communicationequipment, wherein the control information that is obtained on thereception side is information that shows a condition of a communicationline from the transmission side to the reception side, wherein the errordetection unit detects, when communications are implemented by embeddingother optional data in main communication data in communications fromthe transmission side to the reception side, an error of communicationdata, and wherein, when the error of communication data is detected dueto a condition of the communication line, the control informationembedding unit embeds information about the error detection as thecontrol information; and a normal data reception amount monitoring unitto monitor a reception amount of the other optional data before theerror of communication data is detected, wherein the control informationembedding unit further embeds a normal data reception amount in additionto the information about the error detection when the error ofcommunication data is detected.
 5. The interactive communication systemaccording to claim 4, wherein: when communications are implemented byembedding the other optional data in the main communication data incommunications from the second communication equipment to the firstcommunication equipment, the error detection unit detects an error ofthe communication data and when an error of the communication data isdetected, the control information embedding unit embeds informationabout the detected error as the control information; and the secondcommunication equipment further comprises an embedding re-executioncontrolling unit to control re-execution of embedding the other optionaldata in accordance with the information about the detected errortransmitted from the first communication equipment.
 6. The interactivecommunication system according to claim 5, wherein: the firstcommunication equipment further comprises a normal data reception amountmonitoring unit to monitor a normal reception amount of other optionaldata embedded in main communication data transmitted from the secondcommunication equipment and, when the error of the communication data isdetected, the control information embedding unit embeds informationabout a normal data reception amount before the error is detected as thecontrol information in addition to information about the detected error;and an embedding re-execution controlling unit on a side of the secondcommunication equipment controls re-execution of embedding the otheroptional data by eliminating a part shown by the normal data receptionamount.
 7. A communication control method in an interactivecommunication system including a plurality of communication equipmentsthat are connected to each other via a communication line, comprising:receiving reception error information at a reception side; controllingtransmission to the reception side from a transmission side using thereception error information; detecting transmission error ontransmission from the reception side; notifying the reception side ofthe transmission error when the transmission error is detected;embedding, on a side of a first communication equipment, controlinformation that is used for a control of communications from a side ofa second communication equipment in a normal communication data withoutchanging a format of voice code data in a voice communication;controlling, on the side of the second communication equipment,communications to the side of the first communication equipment usingcontrol information transmitted from the side of the first communicationequipment, wherein the control information that is obtained on thereception side is information that shows a condition of a communicationline from the transmission side to the reception side, wherein the errordetection step detects, when communications are implemented by embeddingother optional data in main communication data in communications fromthe transmission side to the reception side, an error of communicationdata, and wherein, when the error of communication data is detected dueto a condition of the communication line, the control informationembedding step embeds information about the error detection as thecontrol information; and monitoring a reception amount of the otheroptional data before the error of communication data is detected,wherein the control information embedding step further embeds a normaldata reception amount in addition to the information about the errordetection when the error of communication data is detected.